In the aluminum industry, it is a common practice to convey aluminum in insulated troughs or filter boxes comprising a steel shell in which a refractory working lining is mounted to resist molten aluminum attack. Because the refractary working lining is usually quite thermally conductive, a good insulating material has to be placed between the refractory working lining and the steel shell to reduce heat losses. Such an insulating material can be called “back-up insulating material”, alternatively referred to herein as insulation material and/or granular material.
An example of an insulation material presently in use is sold under the trademark WOLLITE®. This material which forms the subject matter of U.S. Pat. No. 5,360,771, the disclosure of which is herein incorporated by reference, is a solid, light weight mineral foam obtained by reaction of a wollastonite suspension containing a small quantity of calcium carbonate with a phosphoric acid solution. In addition, E-ZPOUR™ by RexRoto, a non-free flowing vermiculite powder, has been used as an insulating material.
Free flowing granular insulation materials also can be used in a catalytic converter apparatus for use in an exhaust system of an internal combustion engine. The converter includes: a housing, the housing including a gas inlet and a gas outlet; and at least one substrate element arranged in the housing, the at least one substrate element including catalytic material, the at least one substrate element divided into a plurality of zones, each of the zones defining a generally separate flow passage connecting the inlet and the outlet in fluid communication. A granular insulation can be used to form at least one wall at least partially separating the plurality of zones.
A method of reducing emissions from an internal combustion engine can include providing the catalytic converter apparatus as described above and placing the inlet of the apparatus in fluid communication with an exhaust gas stream of the engine